Numerous situations arise in which it is desired to confine a bed of solid fuel to a restricted area of a fuel-supporting surface and then to be able to control or adjust the flow of combustion air to the burning fuel.
For example, it has heretofore been recognized that it is sometimes desired to use a conventional charcoal-burning barbecue to grill or cook a relatively small amount or portion of food and that, in such a situation, it is wasteful of charcoal and ignition fluid to have to fill the barbecue from rim to rim with charcoal briquettes. Difficulties arise, however, if is attempted to confine the briquettes to a limited area of the barbeque since frequently it then becomes difficult in practice to build up a physically stable and sufficiently deep bed of briquettes to establish the proper cooking conditions.
In U.S. Pat. No. 4,592,334, there is provided a device for confining a bed of charcoal briquettes to a restricted area of such a barbecue and, while that device does to a considerable extend achieve the desired result, its use in practice present certain problems.
It is generally accepted that, for the successful operation of a charcoal-burning barbecue with no auxiliary heating system, it is necessary to establish a hot bed of charcoal of fairly uniform temperature throughout. Obviously, the larger the bed both in diameter and depth, the more easily such a uniform temperature can be established. When the charcoal bed is confined to a restricted area of the barbecue, there is a much greater likelihood of there occurring a non-uniform bed temperature. One important cause of this is from the effect of any wind blowing across the charcoal bed. For example, such a wind may cause the upper surface of the charcoal bed to burn overly vigourously while allowing combustion of the lower portion of the charcoal bed to slow down and so fall to a lower temperature. On the other hand, with a stronger wind, combustion at the windward side of the charcoal on its top surface may be totally eliminated. These effects can even lead to total combustion failure.
It is accordingly an important object of this invention to provide a draft controller for use with a conventional charcoal-burning barbecue and by means of which the bed of burning charcoal can be confined to a restricted area of the barbecue while at the same time providing means whereby the draft to the charcoal can be controlled to optimize the maintenance of a uniform temperature throughout the bed of burning charcoal.
It is another object of the invention, in accordance with another feature thereof, to provide a draft controller for the aforesaid purposes and which draft controller can be packaged and stored in a relatively compact form.
Other objects of the invention will become apparent as the description herein proceeds.